Java Language Fundamentals 5 Min Drill
- Real-world objects share two characteristics i.e.
state and behavior
- An object is a software bundle of related state and
- An object stores its state in fields/variables and
exposes its behavior through methods/functions.
- Methods operate on an object's internal state and
serve as the primary mechanism for object-to-object communication
- Hiding internal state and requiring all interaction
to be performed through an object's methods is known as data
- A class is a blueprint or prototype from which
objects are created.
- Common behavior can be defined in a superclass and
inherited into a subclass using the extends keyword.
- Inheritance provides a powerful and natural
mechanism for organizing and structuring your software.
- Object-oriented programming allows classes to
inherit commonly used state and behavior from other classes.
- An interface is a contract between a class and the
- Implementing an interface allows a class to become
more formal about the behavior it promises to provide.
- A collection of methods with no implementation is
called an interface.
- A namespace that organizes classes and interfaces
by functionality is called a package.
- If your class claims to implement an interface, all
methods defined by that interface must appear in its source code
before the class will successfully compile.
- When a class implements an interface, it promises
to provide the behavior published by that interface.
- A package is a namespace that organizes a set of
related classes and interfaces.
- The term API stands for Application Programming